Arduino MEGA 2560 R3 Board is a power house from Arduino list of AVR boards. This big board is build around Atmega2560 microcontroller (datasheet). It has 54 digital I/O lines, 14 of them can be used as PWM outputs. 16 Analog inputs, big 256K flash memory for your code with 16 MIPS speed. 4 Hardware serial ports, USB, power socket an ICSP header and reset button. It contains everything needed to support the microcontroller. This Atmega2560 board is fully compatible with Arduino software. USB to serial is done by Atmega16U2 chip using software CDC stack.